Air separation sorbents: Mixed-cation zeolites with minimum lithium and silver.

Highlights • LSX containing minimum Li and Ag were prepared and evaluated for air separation. • ion exchange procedures were designed to miniemize Li+ on inaccessible sites. • The mixed-cation LSX were compared against pure Li-LSX for air separation by PSA. • The mixed cation zeolites show promising performance for replacing Li-LSX. Abstract Mixed-cation LiSr-LSX, AgCa-LSX and AgSr-LSX containing minimum lithium and silver were prepared by exchanging small fractions of Li+ into Sr-LSX and Ag+ into Sr-LSX and Ca-LSX. To avoid diffusion of the Li+ into the inaccessible sites, the LiSr-LSX sample was exposed to a specifically derived dehydration condition. Similarly, the mixed-silver cation samples were treated to the selected condition post-ion-exchange to allow the Ag+ to migrate into SII*. Strong evidences were provided that significant fractions of the exchanged Li+ and Ag+ remained in SIII and SII* respectively after comparisons of the N 2 /O 2 adsorption isotherms and isosteric heats of adsorption of the mixed-cation and single-cation samples. Furthermore, the mixed-cation LiSr-LSX, AgCa-LSX and AgSr-LSX samples were compared against the single-cation Li-LSX sample based on their O 2 productivity performance via a PSA simulation model. [ABSTRACT FROM AUTHOR]